1. Field of the Invention
The present invention relates to an apparatus for cooling a thin amorphous strip from molten metal by rapidly solidifying using a single roll method and for separating the strip from a cooling roll and smoothly running and guiding the separated thin strip for further processing, for example, to a coiling system.
2. Description of the Prior Art
The prior art discloses cooling a thin metal strip directly from molten metal by bringing the molten metal by a nozzle into contact with the peripheral surface of a cooling roll rotating at a high speed, casting and solidifying the metal. This is conducted in different ways broadly classified as the "single roll method" and the "twin roll method".
The single roll method is suitable for production of a thin metal strip having substantial width. In the single roll method the molten metal is ejected from a nozzle onto a roll rotating at a high speed. Consequently the molten metal forms a deposit which is spread to form a thin layer and is rapidly solidified to form an amorphous metal after the roll surface has moved a predetermined distance, i.e., after a predetermined angle of rotation of the roll. The amorphous metal is progressively separated from the roll surface by the centrifugal force generated as a result of rotation of the roll, so as to form a thin strip.
This single roll method, however, is generally run at a high producing speed of 20 m/sec or higher. In addition, the thickness of the thin metal strip formed by this method is 50 .mu.m or below. Therefore, it has been difficult to separate the thin strip from the cooling roll reliably and to smoothly run and guide the separated strip to a subsequent apparatus, such as a pinch roll or a coiling system.
Japanese Patent Laid-Open Nos. Sho 57-39030 and Sho 57-94453 disclose separating a thin amorphous strip by solidifying from a cooling roll using an air jet. Employing an air jet has the disadvantage that the separation point of the thin strip produced by solidifying is unstable. When applied to a thin strip produced by solidifying and having substantial width, the thin strip separated from the cooling roll tends to run in a curved path, or to roll and break.
In employing an air jet, separation is unstable because the attaching force of the thin strip to the cooling roll changes with time, and differs in the width direction of the thin strip. This causes a serious problem in production of a thin strip having a width of as much as 150 mm or above by solidifying.
Japanese Patent Laid-Open No. Sho 54-50433 and Sho 59-27720 disclose a method of separating a rapidly solidified thin strip by a magnet roll or a magnet conveyor. This method is effective for a narrow thin strip having a low force of attachment to the cooling roll and which attaches to the cooling roll uniformly in the width direction. However, when this method is applied to a thin strip having a width of 150 mm or above, it is not possible to stabilize the path of the thin strip separated from the cooling roll. Consequently, the solidified thin strip tends to be tensioned excessively, and to break.
Japanese Utility Model Laid-Open No. Sho 61-63347 discloses a method of running and guiding a thin strip produced by casting to a coiling drum by pressing a scraper against the cooling roll. This running and guiding method is effective for a rapidly solidified thin strip having a width of 50 mm or below. However, when the width is 150 mm or above, it is not possible to stabilize the path of the thin strip separated from the cooling roll because the separated thin strip tends to stay at the distal end of the scraper. Further, the distal end of the thin strip may pass under the distal end of the scraper, thus making separation very unstable.
Among various proposed methods and arrangements for running and taking up a thin amorphous strip separated from a cooling roll, one practical method is to separate the thin amorphous strip from the cooling roll by causing it to fly suspended in the air along a curved path and to nip the flying strip between pinch rolls to guide the strip for further processing such as a coiling reel. Such a method or arrangement is employed, for example, as a means for taking up a rapidly solidified thin strip in coiling equipment, as disclosed in Japanese Patent Laid-Open Nos. Sho 61-167248 and Hei 1-143720.
The above-described method, however, suffers in that nipping of the flying thin strip in a curved path is difficult and time-consuming, and wastes a quantity of the thin amorphous strip that is produced until the flying strip has been successfully nipped.